Inishtrahull, Co. DonegalIreland's most northerly island. I visited Inishtrahull once, in 2013, aboard the Irish Lights helicopter. We were working our way along the coast after a brutal winter of storms, surveying lighthouse stations for damage, and this was our last stop. The island was abandoned in 1929, when the last families were taken off. Nearly a century later, the lighthouse and its buildings still stand, white and sharp against dark Atlantic rock. What surprised me